Walmart posted weaker-than-expected quarterly earnings on Thursday due to poor U.S. sales and said its profit for this quarter might also miss Wall Street’s forecast.

Everything from pressure on shoppers to a cool start to spring led to an unexpected 1.4 percent drop in sales at Walmart U.S. stores open at least a year, the first drop after six straight gains. Analysts estimated a 0.1 percent decline. Walmart U.S. is by far the company’s largest unit with about 59 percent of sales last year.

Shares of the world’s largest retailer fell 1.7 percent to $78.50 at the close in New York. Walmart has gained 15 percent this year, compared with a 16 percent increase for the Standard & Poor’s 500 Index.

“We hadn’t seen the business turn around particularly in April,” said ITG analyst John Tomlinson. “That was a concern because at that point you would think tax refunds and lower gas prices would have started to help the business.”

Chief Executive Officer Mike Duke has cut prices on groceries and other necessities as the chain’s lower-income shoppers deal with elevated unemployment and increased Social Security taxes.

Duke said in the statement that the first quarter was marked by “considerable headwinds to top line sales” and that the company’s performance will improve throughout the year. Comparable-store sales for Walmart U.S. will be little changed to up 2 percent in the second quarter, the company said.

Unemployment remains “high on the list of concerns” of shoppers surveyed by Walmart, Chief Financial Officer Charles Holley said on a call with reporters Thursday. The U.S. unemployment rate was 7.5 percent in April.

Walmart’s sales slowed in January and February after shoppers’ incomes were reduced by a 2 percentage-point increase in the payroll tax. They also were hurt by tax returns that were delayed because of forms that were shipped late and additional, federally mandated fraud scrutiny.

Jerry Murray, Walmart’s vice president of finance and logistics, said in a Feb. 12 email obtained by Bloomberg News that month-to-date sales had been a “total disaster.” Murray left Walmart last month. Holley said in March that those sales returned to normal by the end of February.

Cooler temperatures also curtailed demand for spring merchandise in North America. Target, the second-largest U.S. discount retailer, said last month first-quarter profit would be less than it previously forecast as cold weather hampered sales of spring merchandise.

Walmart said expenses related to probes of possible violations of the Foreign Corrupt Practices Act in its international operations have been higher than it expected. Those costs were $73 million in the first quarter, more than the $40 million to $45 million it projected. The U.S. Department of Justice and the Securities and Exchange Commission are investigating allegations that Walmart systematically bribed Mexican officials so it could more quickly open stores in the country.

The company said in a November filing that it also has started inquiries into potential violations of the FCPA at operations in Brazil, India and China.